Abstract: A tri-state read-only memory device and its fabrication method are disclosed herein. After a plurality of word lines are formed and spaced apart in parallel through patterning by a shielding layer, insulating blocks are formed to fill the trenches among the word lines. Then removing the shielding layer, sidewalls, of the insulating blocks are revealed, and spacers are formed on the sidewalls thereof. The spacers above the first state regions are removed to form the conductive width of the channel regions in three forms. By merely applying one code-implantation, the ROM device are coded into on of three states at the same time. In addition, the disposition of the insulating blocks by liquid-phase deposition prevents the misalignment that often occurs with the conventional method.